Molecular sieve adsorbents



United States Patent 3,306,922 MGLECULAR SIEVE ADSORBENT S Richard M.Barrer, Bromley, Kent, and Patrick J. Denny, Caversham, Reading,England, and Edith M. Fianigen, Buifalo, N.Y., assignors to UnionCarbide Corporation, a corporation of New York No Drawing. Filed Mar.22, 1961, Ser. No. 97,474 20 Claims. (Cl. 260-448) This inventionrelates to synthetic adsorbent materials and more particularly tosynthetic crystalline forms of nitrogenous aluminosilicate zeolites,derivatives thereof and methods of making these adsorbent materials.

The term zeolite, in general refers to a group of rigid,three-dimensional crystalline, hydrated metal aluminosilicates; some ofthese occur in nature and some have been synthesized. The syntheticzeolite materials of this invention exhibit significant differences inproperties over naturally occurring zeolites and other syntheticzeolites. For convenience and distinguishability, the syntheticmaterials of this invention will be referred to hereinafter as zeoliteNA, zeolite NX, zeolite NY and zeolite N-B wherein the term N designatesan ammonium or alkyl ammonium substituted cationic species, such astetramethylammonium ion and lower derivatives thereof, and the lettersA, X, Y and B designate various types of zeolitic structures containingthe tetrarnethylammonium cation or derivative thereof. openthree-dimensional framework of SiO.; and A tetrahedra. The tetrahedraare cross-linked by the sharing of oxygen atoms, so that the ratio ofoxygen atoms to the total of the aluminum and silicon atoms is equal totwo, or O/(Al+Si)=2. The negative electrovalence of tetrahedracontaining aluminum is conventionally balanced by the inclusion ofalkali metal or alkaline earth metal ions within the crystal in theratio of 2 Al/(ZNa, 2 K, 2 Li, Ca, Ba, Sr, etc.)=1. Moreover it has beenfound in the zeolite art that in some compositions one metal cation maybe replaced for another by suitable exchange techniques. Consequently,crystalline zeolites are often employed as ion-exchange agents.

It is also known that the crystal structures of zeolites possessinterstices of molecular dimensions. The interstitial spaces aregenerally occupied by water molecules. Under proper conditions, viz.,after at least partial dehydration, these zeolites may be utilized asefi'icient adsorbents whereby adsorbate molecules are retained withinthe interstitial spaces. Access to these channels is had by way of poresin the crystal lattice. These openings limit the size and shape of themolecules that can be adsorbed. A separation of mixtures of differentspecies of molecules based upon molecular dimensions, wherein certainmolecules are adsorbed by the activated zeolite while others arerefused, is therefore possible. It is this characteristic property ofmany crystalline zeolites that has led to their designation as"molecular sieves. In addition to molecular size and shape, however,other factors may also infiuence the selective adsorption of certainmolecules by molecular sieves. Among these factors are: thepolarizability and polarity of the adsorbate molecules; the degree ofunsaturation of organic adsorbates; the size and polarizing power of theinterstitial cation; the presence of adsorbate molecules in theinterstitial spaces; and the degree of hydration of the zeolite.

A number of synthetic crystalline zeolites have been prepared. They aredistinguishable from each other, and from naturally occurring materials,on the basis of their composition, crystal structure, adsorbing ability,and other properties. A suitable method for distinguishing thesecompounds, for example, is by their X-ray powder diffraction patternsand the ratio of silica to alumina ice within the crystal structure. Theexistence of a number of zeolites having similar but distinguishableproperties advantageously permits the selection of a particular memberhaving optimum properties for a particular use.

The present invention has as its prime object the provision of novel,synthetic, crystalline zeolites of the molecular sieve type. Anotherobject is to provide novel, synthetic, crystalline zeolites havinguseful ion-exchange and adsorption properties. A further object is toprovide a convenient and efiicient process for preparing the novelmaterials of this invention. Additional objects and advantages Will beapparent from the ensuing disclosure and appended claims.

Heretofore the electrovalent balance within the framework of silica andalumina tetrahedra during synthesis was thought to be only attainable byhaving present in the reactant mixture a substantial quantity of metalcations, such as sodium. Once the metal cation ion had been included inthe reactant mixture and the synthesis reaction completed, the metalions which occupy the cationic sites of the crystal could then bereplaced by a wide variety of other metallic cations using ion exchangetechniques. For the first time in the synthetic zeolite art we haveprepared crystalline zeolites containing a substantial weight percent ofa cation other than sodium or other metal cation. The incorporation ofcations other than metal cations directly into the crystal structure inhigh concentrations during synthesis has not heretofore beenaccomplished. Substitution could in some cases be accomplished byion-exchange methods applied to the crystalline product.

In the novel process of the present invention, nitrogenousaluminosilicate zeolites of the molecular sieve type are produced. Anembodiment of the process of the present invention comprises heating asuitable aqueous reactant mixture containing tetramethylammoniumhydroxide (CH NOH, for the preparation of zeolites NA, NX, and NY, andcontaining ammonium, tetramethylammonium, or lower derivatives oftetramethylammonium hydroxide, such as NH (CH )OH,

NH (CH 0H and NH(CH OH, for the preparation of zeolite NB, and propermixtures of the oxides A1 0 and SiO between about 25l50 C. for zeolitesNA, NX and NY, and between about 200-300 C. for zeolite NB. Othersoluble alkyl-substituted or partially substituted deriva t-ives ofammonium hydroxide such as tetraethylammonium hydroxide may be used tosupply the nitrogenous cationic species to the reactant mixture. Forzeolites such as NX and NY, their more open structure per- 4 mits theincorporation, during synthesis, of larger alkylsubstituted derivativesof ammonium hydroxide such as tetrapropylammonium hydroxide andtetrabutylammonium hydroxide. This mixture is placed in a closedcontainer usually :made of metal or glass. The synthesis reaction isthus conducted under autogenous pressure. For best results, thecrystallization procedure for the preparation of nitrogenous zeolitesN-A, NX and NY is carried out at a temperature of approximately C., thepressure being atmospheric or at least that corresponding to the vaporpressure of water in equilibrium with the mixture of reactants at ahigher temperature. Any suitable heating apparatus, e.-g., an oven, sandbath, oil bath or jacketed autoclave, may be used. Heating is continueduntil the desired crystalline zeolite product is formed. The zeolitecrystals are then filtered off and Washed to separate them from thereactant mother liquor. The zeolite crystals should be washed,preferably with distilled water, until the efiiuent wash water, inequilibrium with the product, has a pH of between about 9 and 11. Otherzeolite types may be produced according to the teachings of thisinvention.

In the preparation of zeolites NA, NX and N-Y, crystallizationtemperatures below C. require extremely long crystallization times.Above about 150 C. other crystalline aluminosilicates are formed insubstantial quantities in addition to or instead of the desired NA, NX,or NY.

In the product-ion of nitrogenous aluminosilicate zeolites according tothe present invention, the reactants are combined as aqueous mixtureshaving in the aggregate an overall composition, conveniently expressedin terms of oxide mole ratios, defined in the general case as follows:

where R is ammonium, alkyl-substituted or partially substitutedderivatives of ammonium, and where the values of a, b, and c are definedas the essential determinants for the production of the desired type ofzeolite. The composition of the initial reactant mixture is critical.

In the production of tetramethylammonium zeolite NA, reactant mixturesmay be employed having a composition, expressed in terms of oxide moleratios, within the following range:

where R is tetramethylammonium ion. A preferred range of initialreactant compositions is as follows:

Range 1 Range 2 RgO/;\l203 equals About 1.5. About 1.5. SiO /AIQO;equals. About 6-.." 2-6. IIgO/AlzOa equals 120-400 120-460.

where R is trimethylammonium ion for range 1, and R is dimethylammoniumion for range 2. In the preferred process for production of zeolite NB,R is dimethylammoniurn ion.

We have found that small quantities of alkali metal cations in thereactant mixture are beneficial for the production of nitrogenouszeolites by the process of this invention, but that it is not necessaryto have a high percentage of the alkali metal cations present in theinitial reactant mixture. The presence of small quantities of alkalimetal cations greatly reduces the time necessary to form crystallinezeolites by this invention. This was substantiated by (1) preparingzeolite N-A in a soft glass reaction vessel, using a colloidal silicasol having 29.0 to 30.0 wt.-percent silica as a silica source whichcontained up to several tenths of a wt.-percent Na O (2) preparingzeolite NA in a stainless steel reaction vessel, using the same silicasource as in (1); and (3) using a stainless steel reaction vessel butusing an ammoniumstabilized silica source which contained less than 0.01wt.-percent Na O. The results were as follows:

An additional comparable amount of N830 was provided by the soft glassreaction vessel.

In the production of tetramethylammonium zeolite NX, reactant mixturemay be employed having a composition, expressed in terms of oxide moleratios, within the following range:

In the production of tetramethylammonium zeolite NY, reactant mixturesmay be employed having a composition, expressed in terms of oxide moleratios within the following range:

R20/A1203 1.52.5 t0 H20/A1203= Thus, it is shown that small quantitiesof sodium greatly reduce the time within which crystallization willoccur.

The reactant mixture of Run 3 eventually produced crystalline zeolite NAmaterial. Within the temperature range of about -150 C., crystallizationtimes of from about 3 to 8 days are suitable.

The compositions of nitrogenous crystalline zeolites may bestoichiometrically expressed in terms of moles of oxides, as: l.OiO.lR,O:Al O :zSiO :yH O wherein R represents an ammonium or alkylammoniumcation; 21 represents the valence of R; z is the moles of silica; and yis the moles of water and usually has a value from 0 to about 7.

When sodium or other alkali metal ion is present in the reactantmixtures used to prepare nitrogenous zeolites by this invention, thecomposition of nitrogenous crystalline zeolites may be expressed interms of moles of oxides as:

wherein R represents an ammonium or alkylammonium cation, M representsalkali metal cation, preferably sodium, x represents the alkali metalcation fraction within the crystal and has a value less than 1, z is themoles of silica and y is the moles of water and usually has a value from0 to about 7.

The composition of tetrarnethylammonium zeolite NA, may be representedas follows:

wherein R represents the tetramethylarnmoniurn cation; when alkali metalcation is present, the composition may be expressed as:

wherein R represents the tetramethylammonium cation, M represents alkalimetal cation, preferably sodium, x represents the alkali metal cationfraction of M within the crystal structure and may vary from 0 to about0.9. Usually x varies from 0 to about 0.5.

The general formula for the product composition of tetramethylammoniumzeolite, NX, may be represented as follows:

wherein R represents the tetramethylammonium cation and M and x are asdefined above.

The general formula for the product composition of tetramethylammoniumzeolite NY, may be represented as follows:

wherein R represents the tetramethylammonium cation, 2 represents themoles of SiO and has values greater than 3 to about 6, M and x are asdefined above.

The general formula for the product composition of nitrogenous zeoliteNB, may be represented as follows:

wherein R represents ammonium, tetramethylammonium or lower derivativesof tetramethylammonium, such as mono-, di-, and tri-methylammonium and Mand x are as defined above.

The maximum value of x for the nitrogenous zeolites is determined by thelimitation that, by definition, the minimum number of alkylammoniumcations per unit cell, which is the smallest entity of repeated order inthe crystal structure, is one. Using this limitation and the unit cellcomposition and cation density of the specific nitrogenous zeolitestructure, the maximum value of x can be calculated. This calculationfor type NA zeolite is given below.

6 enous zeolites of this invention. A number of the tables are directedto the general X-ray pattern of a particular zeolite, namely, Tables A,B, D and F. The remaining tables identify products of specific examples.

In obtaining the X-ray powder diffraction patterns, standard techniqueswere employed. The radiation was the K-alpha doublet of copper; atGeiger counter spectrometer with recorder was used for the patterns ofTables A, B, C, D and E. The peak heights, I, were read from thespectrometer chart. From these, the relative intensities, l00 I/l whereImax, is the intensity of the strongest line or peak, and d (A), theinterplanar spacing in Angstroms, were determined.

In Table F and in Example 1, the diifraction pattern was recorded withan X-ray film camera. Inherently the film technique has somewhat lessaccuracy in the measurement of both d-spacings and intensities than theGeiger counter spectrometer method. The particular X-ray technique and/or apparatus employed, the humidity, the temperature, the orientation ofthe powder crystals and their size and other variables, all of which arewell known and understood to those skilled in the art of X-raycrystallography or diffraction, can cause some minor variations inintensities and positions of the lines.

Although zeolite NA described herein shows some structural similaritiesto the as-synthesized or sodium form of type A (Na A) zeolite identifiedin U.S. Patent 2,882,- 243, issued April 14, 1959, to R. M. Milton,zeolite NA may among other ways be distinguished from Na A and fromother zeolites and silicates by differences in its X-ray powderdiffraction pattern, chemical composition, ion-exchange properties andadsorption properties. The X-ray powder diffraction pattern of zeoliteNA is given in Table A. Significant differences between the d-spacings,relative intensities and unit cell size of zeolites NA and Na A areapparent from a comparison of Table A herein, with Table A in U.S.Patent 2,882,243, e.g., for NA the cubic cell constant a is 12.12 A.,and for Na A, a is 12.32 A.

It is of further importance to note the marked differences in the molarsilica-to-alumina ratios of Na A zeolite and of the NA zeolite of thisinvention. The silica-toalumina ratio of Na A zeolite varies from about1.35 to about 2.35, and is usually synthesized with a ratio of about 2.The silica-to-alumina ratio of the crystalline NA zeolite material ofthis invention is between about 2.5 to 6.0. Thus, for the first timethere has been produced a highly siliceous crystalline zeoliteexhibiting some structural similarities to type A zeolite. Thesilica-rich structure of zeolite NA results in a significant increase III III IV V VI Anhydrous Stoichio- Total No. of No. of Alkyl No. ofAlkali m t Nitrogenous metric Composition Anhydrous Unit Cations.Ammonium Metal 0 p Zeotite in Oxide Ratios Cell Composition 1 Unit CellCations, Cations, Unit Cell Unit Cell kaolumn IV llCgO-AlzOml-SSiOz [M01[:UOzLflSiOlm. 11 1 10 0.91 ME: *Al2O3.6.0Si02 [MeLflAlOgLJSlOflmi 6 1 50- 83 1 Where Me refers to a monovalent cation.

It can be seen from the above data that the maximum value of x for anyone nitrogenous zeolite species is obtained at the minimum mole ratio ofSiO /Al O corresponding to the maximum cation density. Maximum values ofx obtained for several other nitrogenous zeolite species by this methodare shown below:

Nitrogenous zeolite: Maximum value of x N-Y 0.99 NB 0.8

Tables A through F appearing herein set forth the in structuralstability over that of the less siliceous zeolite NagA.

In addition to the differences in molar SiO /Al O ratios hereinabovedescribed, zeolite NA may be distinguished from Na A on the basis ofcation composition, as shown by the general formula for the productcomposition of tetramethylammonium zeolite NA given hereinabove. It isimportant to note that a tetramethylammonium form of zeolite Na A cannotbe prepared by any known ion-exchange method, since the radius of thetetramethylammonium ion is too large to enter the pores in the structureof Na A. This is demonstrated by the fol- X-ray powder diffractionpatterns of the various nitroglowing example, wherein Na A was treatedby the customary ion-exchange technique employing treatment of thezeolite with an aqueous solution of a water-soluble salt of theexchanging ion. Sodium zeolite A was successively treated with portionsof one liter of 1N tetramethylammonium bromide solution, washed withdistilled water until free of bromide ion, and analyzed for nitrogencontent. The product was found to contain less than 0.1 wt.-percent N,showing that essentially no exchange of the tetramethylammonium ion hadtaken place.

The size of the (ClH N" cation is greater than the size of the pores inthe NA zeolite structure; hence, once this cation has been incorporatedin the NA zeolite structure by the synthesis method of the invention, itcannot be removed from this structure by the conventional ion-exchangetechniques. For example, using the ion-exchange procedure describedhereinabove, treatment with calcium chloride and sodium chloridesolutions did not produce any exchange of the calcium or sodium with theincorporated (CH N+ ion in the NA structure. If however Na+ and (CH N+ions are present in the reactant mixture and are subsequentlyincorporated in the synthesized NA crystals, the Na+ ions present in theNA crystal structure may be subsequently ion-exchanged with other metalcations, notably those of K, Li, Ca, Ba, Sr, etc. For example,tetramethylamrnonium NA zeolite containing 4.4 wt.-percent Na O wasprepared. This NA zeolite was then ion-exchanged with a calcium chloridesolution; the analysis of the product showed that all of the sodium ionoriginally present in the NA zeolite had been exchanged with calcium butthe tetramethylammonium content of the NA zeolite structure remainedunchanged. Thus, it is possible to prepare a zeolite structure havingboth exchangeable and non-exchangeable cations and having apredetermined quantity of exchangeable cation sites.

Having a zeolite with a predetermined quantity of exchangeable cationspermits one to introduce a controlled quantity of a particular cationinto a desired process stream.

The following examples are representative of the processes for producingthe zeolites of the present invention:

EXAMPLE 1 Preparation of zeolite NA A solution of tetramethylammoniumaluminate was prepared by dissolving 10.0 g. of freshly precipitatedAl(OH) in a solution containing 29.0 g. of

in 180 g. of water. The solution was then added to 63.8 g. of an aqueouscolloidal silica sol containing 29.5 percent silica by weight. Theresultant reaction mixture, having a composition, expressed in terms, ofmoles of oxides, as follows:

was stirred until homogeneous. Crystallization of the desired zeoliteproduct was carried out by heating the reaction mixture in a sealedstainless steel container at a temperature of 100 C. for about 8 days.The crystalline product which formed was separated from the reactantmother liquor by filtration, washed with water until the effiuent washwater had a pH of about 9 to 11 and dried. X-ray analysis of the productrevealed the powder diffraction pattern shown below, wherein thelettered intensity designations are as follows: VS=very strong,S=strong, MS=medium strong, M=medium, MW=medium weak, W=weak. Thispattern identifies the product as zeolite NA.

d, A.: Relative intensity 12.1 :003 S 8.60 :0.03 S 7.02 :0.02 S 6.08:0.01 VW 8 d, A.: Relative intensity 5.44 :0.01 W 4.97 :001 W 4.30 :0.01MW 4.05 :0.01 VS 3833:0004 MW 3659:0004 VS 3365:0004 MS 3243:0004 S2941:0004 S 2856:0004 M 2712:0004 MW 2646:0004 MW 2585:0004 MS 2479:0004W 2429:0004 W 2215:0004 MW 2144:0004 M 2024:0004 M EXAMPLE 2 Preparationof zeolite NA A solution of tetramethylammoniurn aluminate was preparedby dissolving 1.6 g. of freshly precipitated Al(OH) in a solutioncontaining 12.5 g. of

(CH ,NOH- SH O in 14.8 g. of water. The solution was then added to 20.0g. of an aqueous colloidal silica sol containing 29.5 percent silica byweight. The resultant reaction mixture, having a composition, expressedin terms of moles of oxides, as follows:

was stirred until homogeneous. Crystallization of the desired zeoliteproduct was carried out by heating the reaction mixture-in a sealed softglass jar at a temperature of C. for about 2.9 days. The crystallineproduct which formed was separated from the reactant mother liquor byfiltration, washed with water until the efiluent wash water had a pH ofabout 9 to 11 and dried. X-ray analysis of the product revealed a powderdiffraction pattern characteristic of zeolite NA as shown in Table A,with a cubic unit cell constant, a of 12.12 A. Chemical analysis showedthe zeolite product to have a composition, expressed in terms of molesof oxides, corresponding to the formula 0.66[ (CH N] O:0.39Na O:Al O:5.82SiO :6.8H O

As discussed previously, the Na O in the product was derived from thecolloidal silica sol used as a reactant and from the soft glass reactionvessel.

EXAMPLE 3 Preparation of zeolite NA in 157 g. of water. The solution wasthen added to 200 g. of an aqueous colloidal silica sol containing 29.5percent silica by weight. The resultant reaction mixture,

- having a composition, expressed in terms of moles of oxides, asfollows:

3.0[(CH N] O-Al O -10.0SiO -198H O was stirred until homogeneous.Crystallization of the desired zeolite product was carried out byheating the reaction mixture in a sealed soft glass jar at a temperatureof 100 C. for about 5 days. The crystalline product which formed wasseparated from the reactant mother liquor by filtration, washed withwater until the effiuent wash water had a pH of about 9 to 11 and dried.

Relative Intensity s VMMSMMWWSMSMMSMWM MSJ mA A AQmQQQWQWnmZZZZZZZZZZZZZOMVML 1111111 X-ray analysis of the productrevealed a TABLE B.-x RAY POWDER DIFFRACIION DATA FORTETRAMETHYLAMMONIUM ZEOLITE NX hkl 9 "w 1 a 5 9 1 .v y i 7 7 718 4Q. 133" v3 7:0 Y Y I b 7787 1919 101 S 9987 1919 111 mu l 6 1 h2. 1 .mo'. nvw1 0 4 0 0 d awno o nwflwl o awno 5 2 5 111301D.1.3 014411 117,111.121334323343 4164000081121031338343 123334565667 789681111811111111 1line product which formed was separated from the reactant mother liquorby filtration, washed with water Chemical analysis until the effluentwash water had a pH of about 9 to 11 and dried. g to 5 powderdilfraction pattern characteristic of zeolite NX as shown in Table B,wherein the lettered intensity :4.40SiO :4.9H O designations are aspreviously defined.

0 Rd 0 O 9. Z 90 no EXAMPLE 5 Preparation of zeolite NX A solution oftetramethylammonium aluminate was prepared by dissolving 1.3 g. offreshly precipitated I Al(OH) in a solution containing 12.7 g. of (CH).,NOH-5H O in 20.5 g. of water. The solution was then added to 5.0 g.of an aqueous colloidal silica sol containing 29.5 percent silica byweight. The resultant reaction mixture, having a composition, expressedin terms of moles of oxides, as follows:

was stirred until homogeneous. Crystallization of the desired zeoliteproduct was carried out by heating the reaction mixture in a sealed softglass jar at a temperature of 100 C. for about 4.5 days. The crystallineproduct which formed was separated from the reactant mother liquor byfiltration, washed with water until the eflluent wash water has a pHofabout 9 to 11 and dried. .X-ray analysis of the product revealed thepowder diffraction pattern shown in Table C with a cubic unit cellconstant,

0 O 1 0055 6197 66 9 9161 74 n N 8 15 H33H5 0 m 03121461 .181155111 4 rm1 22111114 33 2 a 72 I 11111 111O0OO00O0M0BMWOWWmWOWmWWWMMMMMMMMMOOOOOMOOO.000000O00UO0OOOOOOOOOOOOUOOOOOOOUOO QQQQQQQQQQQ0QQQQQQQQQQQQQQQQQQQQQQQ85962 9 11.511111;iii;iiiiiiiiii 05904 29 50896 3435301118992620714659581 .3 56335 8727351417 1 6 72 3196 O75 S66544O8632987 5443322110 09 8887766 655 4 3333222221ZZZZZZZZZZLLLLLLLLLLLLLL a a a M 4 5 5 O 010032 23 Q .0 220 13 33 h 0 11 0133 23 0 Wed 35 413M54 3 4 4 5534 54 6 5565566556 00100101-01019-Q0122QLLQIOLmled olnlwlzawflwmLmlnn wlwnw 011012211222320 32331OZZ 33 11241230110.2235 11122 .223333334 344.45555.0466656677777776 TETRAMETHYLAMMONIUM ZEOLITE NA X-ray analysis of theproduct revealed a powder diffraction pattern characteristic of zeoliteNA as shown in Table A (X-ray data for NA). showed the zeolite productto have a composition, expressed in terms of moles of oxides,correspondin the formula:

O.50[(CH3)3 2N]2O10.40N32OIA12O3 again, the Na O in the product wasderived from the colloidal silica sol used as a reactant and from thesoft glass reaction vessel.

TABLE A.-X-RAY POWDER DIFFRACTION DATA FOR EXAMPLE 4 Preparation ofzeolite NX of freshly precipitated Al('OH) in a solution containing 6.75g. of

cH ,NoH-5H o The solution was then added to 5.0

ica sol containing 29.5 per- 6 The resultant reaction mixture, having acomposition, expressed in terms of moles of A solution oftetramethylammonium aluminate was prepared by dissolving 2.33 g.

in 30.5 g. of water. g. of an aqueous colloidal sil cent silica byweight.

oxides as follows:

was stirred until homogeneous. Crystallization of the desired zeoliteproduct was carried out by heating the reaction mixture in a sealedstainless steel container at a temperature of C. for about 8 days. Thecrystal- RAY POWDER DIFERACIION DATA FOR MMONIUM ZEOLITE N-Y zeolite N-Yas shown in Table D wherein the lettered intensity designations are aspreviously defined.

TABLE D.-X

FOR TETRAMETHYLA a of 24.92 A. This pattern is characteristic of zeoliteN-X as shown in Table B.

we s an s11 iivvv w i www ww w www ww w amVnnSNL\\\SnySA1Sn\nVVVAVV\V\VVV XV V\W 1 R 579m --369849-3809341050651nl48409 39 639 16367 3108- 642088- 66544329110008 8H1 rip/6 Awhom1&4AiiaamnaaomflwlllllilllllllZZOML LL LLL 1 chmmhcnvmlao. o o34378.:.91{vw1m.m L3; my 1: ll 385- 49 9' 643098- 654439-27.11009 88 7 M&754-44-4 &3 &3 33m21221222221221221 LL LLL 3 9 a, 6 s, s 5 1 1 7 0 0 7 11 9 .1 l 5 .1 .1 0 5 1 3 5 5 Q I 70 7 h 7 7 718 0264 5 134 1. 1 15 1.y 1. 6666-l /780 19 101 88687 9981 19 111 H R MM w 0 0 2 0 1 6 0 n 2. 1-ma 1 04 5 4 5 657 11111 1111111.. 111 1 1 1 1 1 02241 33058133 525 n.nmnmnwnmanownnwnanemmmtmtta & 1 ,s 1 1 a 1 r 1 1i 3334-U6656P 678n896811lllslllllmmmwmn h 0 .O 0 5 0 .D 1 1 2 2 3 3 R O 0 F 0 1 \1 X 05093713 1 71 6 T, a- 18 3 M3418143n ul2h -3111134 X x 1 A2 m DN H I E OT m Tco 1.13111 mamammmmmmmmmmmmmmmmmmmmmmmm Rnm UUNUOOO00.00000000000000000000000000 1 A iiiiiiiiiii iiiiiiif; 201.2011.mwmnwwamaawaanmwnmwmwgwnmw U 10 48578429863098776544332110099887777 DM&7 54 4 4 3 &&a3 2 222221122222LZLLLLLLLL 1 0 H E 1 pm 7 1 m Y 9 P 6 yT 1 cm M 7 0 U 7 1 R i 1 19 .1 .A k 5 1.1 0 YR 1 5 13 5 5 A l 9 I 7 70 T77 718 026 134 7 1 15 1 1 1 C 6 106 r 8 119 101 T 8868 9987 119 111 l 053 1.1.1.1 .111; .1.1.1 .1.1.1 E 1 G5 5 0020 13012113 104 5 657 111111111111 111 L 1 11 1 0224 33058133 525 10113010319-39-101 4 l rvo lyvyyvis 1)) B 19.13343u4 031 3-2541 400008119-103338343 A 1r -333456566n8n 89681111811111111811. T

EXAMPLE 7 Preparation of zeolite N-Y The resultant reaction mix- 2.5[(CHN] O-Al O -3.4SiO -3.1411 0 X-ray analysis of the product revealed theChemical analysis showed the product zeolite to have a composition, ex-

:Al O :3.46SiO :4.5H O

A solution of tetramethylammonium aluminate was prepared by dissolving4.76 g. of freshly precipitated Al(OH) in a solution containing 27.0 g.of

in 122 g. of water. The solution was then added to 20.0 g. of an aqueouscolloidal silica sol containing 29.5 percent silica by weight. ture,having a composition, expressed in terms of moles of oxides, as followstemperature of 100 C. for about 13 days. The crystalline product whichformed was separated from the re- 65 actant mother liquor by filtration,washed with water cell constant, :1 of 24.81 A. This pattern ischaracteristic m the rea tan m t 70 of zeolite N-Y as shown in Table D.washed with water until the effluent Cubic, (10:24.92 A.

EXAMPLE 6 Preparation of Zeolite N-Y A solution of tetramethylammoniumaluminate was prepared by dissolving 1.15 g. of freshly precipitatedAl(OH) in a solution containing 6.75 g. of

(CH NOH-5H O The resultant reaction mixture, expressed in terms of molesof 59 was stirred unt1l homogeneous. Crystalhzatronof the desiredzeollte product was carried out by heating the reaction mixture in astainless steel reaction vessel at a until the efiluent wash water had apH of about 9 to 11 and dried. powder ditfraction pattern shown in TableE, with a unit The crystalline prod- 1 a d d i Y pressed in terms ofmoles of oxides, corresponding to the powder diffractiton f la;

ic unit cell con- (I of 24.81 A. This pattern is characteristic of in30.5 g. of water. The solution was then added to 5.0 g. of an aqueouscolloidal silica sol containing 29.5 percent silica by weight.

having a composition,

oxides, as follows:

was stirred until homogeneous. Crystallization of the desired zeoliteproduct was carried out by heating the reaction mixture in a sealed softglass jar at a temperature of C. for about 8 days.

uct which formed was separated fro liquor by filtration,

wash water had a pH of about 9 to 1 analysis of the product revealed thepattern shown in Table E, with a cub stant,

TABLE E.XRAY POWDER DIFFRACT'ION DATA FOR TETRAMETHYLAMMONIUM ZEOLITEN-Y l1 kl (I, A I/ mnx. X100 v 1428i. 02 100 8.775;. 02 18 71481.02 175. 69:1; 01 ll 4. 781-.01 l 4. 139i. ()1 7 4 4.. 1 3. T 3. l0 3. 9 3. l3. l7 3. 6 2. 8 2. 17 2. (i 2. 2 2. T 2. 2 2. 1 L, 2. 1 2. 4 10, 4, 0;864 2. l 11,1,1;7T5 2." 1 880 2. 2 l1, 3, 1; 971; 95a 2. 2 l1, 3, 3; 9732. 1 12, O, 0;884 2. 1 11, 5, 2;10, T, l, 10, 5, 5 2. l 10, 8, 2 1. 213, 1, 1; 11, 7, 1; l1 5, 5; 992 1. 1 13, 3, 1; 11, 7, 3; 977 1. 1 l3,3, 3; 995 1. l 888 1. 1 l3. 5,1;11, 7,5 1." 1 14, 2, O; 10, 10, 0; 10,8, 6 1. 2 13, 5, 4;11, 8, 5 1. 2

Cubic, 110 21.81 A.

EXAMPLE 8 Preparation of zeolite N-B A solution or trimethylarnmoniumaluminate was prepared by dissolving 10.0 g. of freshly precipitatedAl(OH) in a solution containing 14.8 g. of (CH NHOH in 180 g. of water.The solution was then added to 63.8 g. of an aqueous colloidal silicasol containing 29.5 percent silica by weight. The resultant reactionmixture, having a composition, expressed in terms of moles of oxides, asfollows:

1.5[ (CH NH] O Al O 6.0SiO 200E1 0 was stirred until homogeneous.Crystallization of the desired zeolite product was carried out byheating the reaction mixture in a stainless steel reaction vessel at atemperature of 300 C. for about 3 days. The crystalline product whichformed was separated from the reactant mother liquor by filtration,washed with water until the effluent wash water had a pH of about 9 to11 and dried. X-ray analysis of the product revealed a powderdiffraction pattern characteristic of zeolite N-B as shown in Table F,with a cubic unit cell constant, (1 of 10.02 A.

TABLE F.X-RAY POWDER DIFFRACIION DATA FOR znonrrn N-B Cubic 1 :10.02 A.

EXAMPLE 9 Preparation of zeolize N-B with dimethylammonium hydroxide Asolution of dimethylammonium aluminate was prepared by dissolving 10.0g. of freshly precipitated Al(Ol-I) in a solution containing 12.1 g. of(CH NH OH in 180 g. of water. The solution was then added to 31.9 g. ofan aqueous colloidal silica sol containing 29.5 percent silica byweight. The resultant reaction mixture, having a composition, expressedin terms of moles of oxides, as follows:

was stirred until homogeneous. Crystallization of the desired zeoliteproduct was carried out by heating the reaction mixture in a stainlesssteel reaction vessel at a temperature of 200 C. for about 6 days. Thecrystalline product which formed was separated from the reactant motherliquor by filtration, washed with water until the etfiuent wash waterhad a pH of about 9 to 11 and dried. X-ray analysis of the productrevealed a powder diffraction pattern characteristic of zeolite N-B asshown in Table F with a cubic unit cell constant, n of 10.02 A. Chemicalanalysis showed 3.97 wt.-percent N, 5.32 wt.- percent C, and 2.84wt.-percent H, giving a mole ratio of methyl to nitrogen in the productof 1.56.

The zeolites of the instant invention are amenable to a wide variety ofapplications such as separation of one fluid species from a streamcontaining many species by adsorption either preferentially or on thebasis of the molecular dimensions of a particular fluid species. Forsatisfactory use as an adsorbent, the zeolite of this invention shouldbe activated by at least partial dehydration. Such activation may beperformed, for example, by heating the zeolite to temperatures ofapproximately C. under atmospheric or reduced pressure, or bymaintaining the zeolite at room temperature under vacuum. Unlike commonadsorbents such as charcoal and silica gel which show adsorptionselectivities based primarily on the boiling point or criticaltemperature of the adsorbate, the activated zeolites of this inventionexhibit a selectivity based on the size, shape, degree of unsaturation,polarity and polarizabiiity of the adsorbate molecule.

It is to be noted that the rejection characteristics of these zeolitesare as important as the adsorption charjected cross-section of theadsorbate molecule. The term may also be defined as the diameter of thesmallest cylinder which will accommodate a model of the adsorbatemolecule using the best available values of bond distances, bond anglesand van der Waals radii. Thus, molecules having criical dimensionsexceeding the pore diameter of a given zeolite will be rejected by thatzeolite, while those having smaller critical dimensions will beadsorbed.

Another property of these zeolites which contributes to its usefulnessis that of adsorbing relatively large quantities of adsorbate at eithervery low adsorbate pressures or concentrations. The novel materials ofthis invention may therefore be utilized as selective adsorbents innumerous gas or liquid separation processes wherein adsorbents generallyare not employed. The use of these zeolites also permits more efiicientand more economical operation of numerous other processes now employingother adsorbents. The zeolites may, for example, be used in the removalof adsorbable impurities from gas and liquid mixtures, or in therecovery of minor components of such mixtures.

Samples of tetramethylammoniurn zeolites NA and N-Y which had beenactivated by dehydration at a temperature of approximately 90 C. undervacuum, were tested to determine their adsorption properties. Theresults obtained are set forth in Table G. The adsorption properties ofthe zeolite samples were measured in a McBain-Bakr adsorption system.The samples were placed in light glass buckets suspended from quartzsprings. They were activated in situ and the gas or vapor under test wasthen admitted to the system. The gain in weight of the adsorbent wasmeasured by the spring extensions as read by a cathometer. In Table G,the pressure given for each adsorption is the pressure of the adsorbate.The term weight percent adsorbed refers to the percentage increase inthe weight of the activated adsorbent.

It is seen from the data of Table G, for example, that molecules such ashaving a critical dimension less than about three Angstroms (A.) aresubstantially rejected by zeolite NA, while molecules such as water andcarbon dioxide of a more polar nature also having critical dimensionsless than about three A. are adsorbed extensively. Zeolite N-Y, forexample, has a pore size substantially greater than that of zeolite N-A.

TABLE G.ZEOLITE N-A Again, zeolite N-A of this invention is furtherdistinguished from the as-synthesized zeolite Na A on the basis ofadsorption characteristics, since the adsorption pore size of zeoliteN-A is about 3 A. and the pore size of Na A is about 4 A. Hence, thepore size difference allows separations of mixtures of molecules basedon the size of the molecules to be carried out using zeolite NA thatcannot be accomplished by zeolite Na A. For example, molecules havingcritical dimensions of about 3.9'A. such as methane may be separatedfrom a mixture of methane and molecules having critical dimensions ofless than about 3 A., such as CO and water. The nitrogenous zeolitesdescribed herein may also be used as desiccants after activation. Forexample, a wet stream of gaseous or liquid hydrocarbons may beefiiciently dried by contacting this stream with activated nitrogenouszeolites of the present invention.

VJ hat is claimed is:

1. A synthetic, crystalline zeolite having a composition expressed interms of moles of oxides as follows:

wherein y is any value from 0 to about 7, said synthetic crystallinezeolite having an X-ray diffraction pattern essentially the same as thatshown in Table A, and the tetramethylammonium cation content of saidzeolite having been introduced thereinto as an incident of the formationof the crystal lattice thereof.

2. A synthetic, crystalline zeolite having a composition expressed interms of moles of oxides as follows:

wherein M represents an alkali metal cation, x represents the fractionof M in the zeolite crystal and having values from 0 to about 0.9, and yis any value from 0 to about 7, and the tetramethylammonium cationcontent of said zeolite having been introduced thereinto as an incidentof the formation of the crystal lattice thereof.

3. A synthetic, crystalline zeolite having a composition expressed interms of moles of oxides as follows:

wherein x represents the fraction of sodium ion in the zeolite crystaland having values from 0 to about 0.9 and y is any value from 0 to about7, said synthetic crystalline zeolite having an X-ray diffractionpattern essentially the same as that shown in Table A, and thetetramethylammonium cation content of said zeolite having beenintroduced therinto as an incident of the formation of the crystallattice thereof.

4. A synthetic, crystalline zeolite having a composition expressed interms of moles of oxides as follows:

wherein x represents the fraction of sodium ion in the zeolite crystaland having values from 0 to about 0.5 and y is any value from 0 to about7, said synthetic crystalline zeolite having an X-ray diffractionpattern esestnially the same as that shown in Table A, and thetetramethylammoniurn cation content of said zeolite having beenintroduced thereinto as an incident of the formation of the crystallattice thereof.

5. A method for synthesizing tetrarnethylammonium zeolite NA whichcomprises preparing at least two separate aqueous mixtures of reactantswhich in the aggregate when mixed contain water, silicate ions,aluminate ions and tetramethylammonium ions in the proportions such thatthe oxide mole ratios of the reactants in the aggregate falls within theranges:

intimately mixing said separate aqueous mixtures to form an aggregatemixture; heating said aggregate mixture to between about 50 C. to C.under autogeneous pressure until crystals of tetramethylammonium zeoliteN-A form; and separating said crystals from the mother liquor.

6. A method for synthesizing tetramethylammonium zeolite N-A whichcomprises preparing at least two separate aqueous mixtures of reactantswhich in the aggregate when mixed contain water, silicate ions,aluminate ions and tetramethylammonium ions in the proportions such thatthe oxide mole ratios of the reactants in the aggregate mixture fallswithin the ranges:

to 3-5 SiO /Al O =about Hgo/Alzog about intimately mixing said separateaqueous mixture to form. an aggregate mixture; heating said aggregatemixture to between about 50 C. to 150 C. under autogeneous pressureuntil crystals of tetramethylammonium zeolite N-A form; and separatingsaid crystals from the mother liquor.

7. A method for synthesizing tetramethylammonium zeolite NX whichcomprises preparing at least two separate aqueous mixtures of recatantswhich in the aggregate When mixed contain water, silicate ions,aluminate ions and tetramethylammonium ions in the proportions such thatthe oxide mole ratios of the reactants in the aggregate mixture fallswithin the ranges:

intimately mixing said separate aqueous solutions to form an aggregatemixture; heating said aggregate mixture to between about 50 C. to 150 C.under autogenous conditions until crystals of tetramethylammoniumzeolite NX form; and separating said crystals from the mother liquor.

9. A method for synthesizing tetramethylammonium zeolite NY whichcomprises preparing at least two separate aqueous mixtures of reactantswhich in the aggregate when mixed contain Water, silicate ions,aluminate ions and tetramethylammonium ions in the proportions such thatthe oxide mole ratios of the reactants in the aggregate mixture fallswithin the ranges:

[(CH N] O/Al O =l.5 to 2.5 SiO /Al O greater than 3 to less than 4 HO/Al O =l2O to 330 intimately mixing said separate aqueous mixtures toform an aggregate mixture; heating said aggregate mixture to betweenabout 50 C. to 150 C. under autogeneous pressure until crystals oftetramethylammonium zeolite NY form; and separating said crystals fromthe mother liquor.

10. A method for synthesizing tetramethylammonium zeolite NY whichcomprises preparing at least two sepa rate aqueous mixtures of reactantswhich in the aggregate when mixed contain water, silicate ions,aluminate ions and tetramethylammonium ions in the proportions such thatthe oxide mole ratios of the reactants in the aggregate mixture fallswithin the ranges:

intimately mixing said separate aqueous mixtures to form an aggregatemixture; heating said aggregate mixture to between about 50 C. to C.under autogeneous pressure until crystals of tetramethylammonium zeoliteNY form; and separating said crystals from the mother liquor.

11. A method for synthesizing trimethylammonium zeolite NB whichcomprises preparing at least two separate aqueous mixtures of reactantswhich in the aggregate when mixed contain water, silicate ions,aluminate ions and trimethylammonium ions in the proportions such thatthe oxide mole ratios of the reactants in the aggre gate mixture fallswithin the ranges:

intimately mixing said separate aqueous mixtures to form an aggregatemixture; heating said aggregate mixture to between about 200 C. to 300C. under autogeneous pressure until crystals of trimethylammoniumzeolite NB form; and separating said crystals from the mother liquor.

12. A method for synthesizing dimethylammonium zeolite NB whichcomprises preparing at least two separate aqueous mixtures of reactantswhich in the aggregate when mixed contain water, silicate ions,aluminate ions and dimethylammonium ions in the proportions such thatthe oxide mole ratios of the reactants in the aggregate mixture fallswithin the ranges:

intimately mixing said separate aqueous mixtures to form an aggregatemixture; heating said aggregate mixture to between about 200 C. to 300C. under autogeneous pressure until crystals of dimethylammonium zeoliteNB form; and separating said crystals from the mother liquor.

13. A method for synthesizing crystalline tetramethylammonium zeolite NAwhich comprises preparing at least two separate aqueous mixtures ofreactants which in the aggregate when mixed contain water, silicateions, aluminate ions, alkali metal ions and tetramethylammonium ions inthe proportions to form crystals of said NA zeolite, said alkali metalions being present in sufficient quantity to yield said NA zeoliteprepared from said aggregate mixture having a final mixed cationiccomposition in accordance with the following composition expressed interms of moles of oxides:

wherein M represents the alkali metal cation, x represents the fractionof M in the zeolite crystal and positive values from O to about 0.9, andy is any value from 0 to about 7; intimately mixing said separateaqueous mixtures to form an aggregate mixture; heating said intimatelymixed aqueous mixture to between about 50 C. to 150 C. under autogeneouspressure until crystals of said molecular sieve form; and separatingsaid crystal from the mother liquor.

14. A method for synthesizing crystalline tetramethylammonium zeolite NAwhich comprises preparing at least two separate aqueous mixtures ofreactants which in the aggregate when mixed contain water, silicateions, aluminate ions, sodium ions and tetramethylammonium ions in theproportions to form crystals of said NA zeolite, said sodium ions beingpresent in sufiicient quantity to yield said NA zeolite prepared fromsaid aggregate mixture having a final mixed cationic composition inaccordance with the following composition expressed in terms of moles ofoxides:

zeolite crystal and having positive values from 0 to about 0.9; and y isany value from 0 to about 7; intimately mixing said separate aqueousmixtures to form an aggregate mixture; heating said intimately mixedaqueous mixture to between about 50 C. to 150 C. under autogeneouspressure until crystals of said molecular sieve form; and separatingsaid crystals from the mother liquor.

15. A method for synthesizing crystalline tetramethylammonium zeoliteN-A which comprises preparing at least two separate aqueous mixtures ofreactants which in the aggregate when mixed contain water, silicateions, aluminate ions, sodium ions and tetramethylammonium ions in theproportions to form crystals of said N-A zeolite, said sodium ions beingpresent in sufficient quantity to yield said N-A zeolite prepared fromsaid aggregate mixture having a final mixed cationic composition inaccordance with the following composition expressed in terms of moles ofoxides:

wherein x represents the fraction of sodium ion in the zeolite crystaland having positive values from to about 0.5, and y is any value from 0to about 7; intimately mixing said separate aqueous mixtures to form anaggregate mixture; heating said intimately mixed aqueous mixture tobetween about 50 C. to 150 C. under autogeneous pressure until crystalsof said molecular sieve form; and separating said crystals from themother liquor.

16. A method for synthesizing crystalline tetramethylammonium zeoliteN-Y which comprises preparing at least two separate aqueous mixtures ofreactants which in the aggregate when mixed contain water, silicateions, aluminate ions, sodium ions and* tetramethylammonium ions in theproportions to form crystals of said N-Y zeolite, said sodium ions beingpresent in suflicient quantity to yield said N-Y zeolite prepared fromsaid aggregate mixture having a final mixed cationic composition inaccordance with the following composition expressed in terms of moles ofoxides:

wherein x represents the fraction of sodium ion in the zeolite crystaland having positive values from 0 to about 0.99 and y is any value from0 to about 7; intimately mixing said separate aqueous mixtures to forman aggregate mixture; heating said intimately mixed aqueous mixture tobetween about 50 C. to 150 C. under autogeneous pressure until crystalsof said molecular sieve form; and separating said crystals from themother liquor.

17. A method for synthesizing crystalline tetramethylammonium zeoliteN-X which comprises preparing at least two separate aqueous mixtures ofreactants which in the aggregate when mixed contain water, silicateions, aluminate ions, sodium ions and tetramethylammonium ions in theproportions to form crystals of said N-X zeolite, said sodium ions beingpresent in sufficient quantity to yield said N-X zeolite prepared fromsaid aggregate mixture having a final mixed cationic composition inaccordance with the following composition expressed in terms of moles ofoxides:

wherein x represents the fraction of sodium ion in the zeolite crystaland having positive values from 0 to about 0.99 and y is any value from0 to about 7; intimately mixing said separate aqueous mixtures to forman aggregate mixture; heating said intimately mixed aqueous mixture tobetween about 50 C. to 150 C. under autogeneous pressure until crystalsof said molecular sieve form; and separating said crystals from themother liquor.

18. A method for synthesizing crystalline trimethylammonium zeolite N-Bwhich comprises preparing at least two separate aqueous mixtures ofreactants which in the aggregate when mixed contain water, silicateions, aluminate ions, sodium ions and trimethylammonium ions in theproportions to form crystals of said N-B zeolite, said sodium ions beingpresent in suflicient quantity to yield said N-B zeolite prepared fromsaid aggregate mixture having a final mixed cationic composition inaccordance with the following composition expressed in terms of moles ofoxides:

wherein x represents the fraction of sodium ion in the zeolite crystaland having positive values from 0 to about 0.8 and y is any value from 0to about 7; intimately mixing said separate aqueous mixtures to form anaggregate mixture; heating said intimately mixed aqueous mixture tobetween about 200 C. to 300 C. under autogeneous pressure until crystalsof said molecular sieve form; and separating said crystals from themother liquor.

19. A method for synthesizing crystalline dimethylammonium zeolite N-Bwhich comprises preparing at least two separate aqueous mixtures ofreactants which in the aggregate when mixed contain water, silicateions, aluminate ions, sodium ions and dimethylammonium ions in theproportions to form crystals of said N-B zeolite, said sodium ions beingpresent in sufficient quantity to yield said N-B zeolite prepared fromsaid aggregate mixture having a final mixed cationic composition inaccordance with the following composition expressed in terms of moles ofoxides:

wherein x represents the fraction of sodium ion in the zeolite crystaland having positive values from 0 to about 0.8 and y is any value from 0to about 7; intimately mixing said separate aqueous mixtures to form anaggregate mixture; heating said intimately mixed aqueous mixture tobetween about 200 C. to 300 C. under autogenous pressure until crystalsof said molecular sieve form; and separating said crystals from themother liquor.

20. A synthetic, crystalline zeolite having a composition expressed interms of moles of oxides as follows:

0.1 to to 'Al O :2.5 t0 4.0SiO :3.5 t0 5.5H O

wherein M is a member selected from the group consisting of sodium andpotassium and the sum of the number of moles of [(C-H N] O and M 0 isbetween 0.9 and 1.1, in which the [(CH N] O content of said zeolite hasbeen introduced thereinto as an incident to the formation of the crystallattice thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,882,243 4/1959Milton 23-1 13 2,950,952 8/1960 Brock et a1 23ll3 FOREIGN PATENTS1,038,015 9/1958 Germany.

OTHER REFERENCES Barrer et al.: Heivetica Chimica Acta, vol. XXXIX,Fasc. II (1956), No. 61.

Barrer et al.: Transactions of the Faraday Society, vol. 54, part 7,July 1958, pages 1074-1085.

TOBIAS E. LEVOW, Primary Examiner.

ABRAHAM H. WINKELSTEIN, Examiner.

I. R. PELLMAN, Assistant Examiner.

1.0$0.1((1-X)((CH3)4N)2O+XM2O3:4.25$ 1.75SIO2:YH2O
 2. A SYNTHETIC,CRYSTALLINE ZEOLITE HAVING A COMPOSITION EXPRESSED IN TERMS OF MOLES OFOXIDES AS FOLLOWS: